The sprinter Dwain Chambers and cyclist David Millar will know by the end of April whether their lifetime bans from the Olympics will be lifted, after the British Olympic Association filed a formal appeal against the World Anti-Doping Agency's decision to rule the BOA noncompliant with its code.

The BOA had been expected to appeal to the Court of Arbitration for Sport since Wada ruled last month that the BOA's ban was not compatible with its universal anti-doping code.

Wada made the decision in the light of an earlier court ruling that struck out an International Olympic Committee rule banning any athlete suspended for more than six months for a doping offence from the Games that followed, allowing the United States Olympic 400m champion LaShawn Merritt to run in London.

The BOA chairman, Lord Moynihan, says its appeal has "every chance" of success, arguing that the BOA's rule is an eligibility criterion and not an additional sanction. But most other legal experts believe it is directly analogous with the IOC's "rule 45", introduced ahead of the Beijing Games in 2008, and the appeal will be rejected.

The BOA rule, introduced in 1992 and applying to any athlete banned for six months or more for drug offences, applies exclusively to Olympics and is now the only lifetime ban in world sport. The BOA claims to have the support of more than 90% of British athletes for the rule.

Its battle with Wada became increasingly vitriolic against the backdrop of a wide-ranging attack on the global agency by Moynihan, who accused it of being "toothless" and called for a fundamental rethink. The Wada director general, David Howman, countered with a lengthy rebuttal and accused Moynihan of launching an "emotional tirade without substance".

The BOA said that one of the reasons for filing the appeal was that the "presence of athletes who deliberately cheat within Team GB would damage team morale, atmosphere and cohesiveness".

Moynihan said: "The BOA selection policy is a direct expression of the commitment British athletes have made to uphold the values of fair play, integrity and clean competition – values that are at the heart of Olympic sport.

"It is a policy that reflects the culture and character of Team GB," he said. "The BOA and British Olympic athletes do not consider that those who have deliberately cheated should represent Great Britain at the Olympic Games."

The BOA said it would be represented by Lord David Pannick QC of Blackstone Chambers, Adam Lewis QC of Blackstone Chambers and Tom Cassels of Baker & McKenzie. The Cas is expected to rule before the end of April.

Millar and Chambers, who received two-year doping bans in 2004 and 2003, respectively, have been reluctant to directly challenge the rule but have indicated they would compete if it was dropped.

Millar, now a vocal anti-doping campaigner, recently accused the BOA of putting politics before athletes, arguing for a consistent set of global rules.

Chambers's agent, Siza Agha, said it was "unfortunate" that the issue would not be decided until the spring and highlighted that several athletes had recently called for an "equal and fair" doping policy for all athletes.

"It is plain that the bylaw is not fair or equal and, if upheld, clean, committed British athletes will be unable to compete at 2012 whilst a host of sanctioned athletes from every single country around the world will do so freely," he said. "In my view, now the decision has been made, it is of absolute priority for all parties to ensure that this matter is expedited through the arbitration process."

He said Chambers, currently on his honeymoon, would defend his world indoor title in March "proudly wearing a British vest".

Agha said: "Dwain is not a lawyer, never wanted to go to court and just wants to be recognised as an athlete after nearly a decade of various, and still ongoing, sanctions laid against him. In the interest of British sport this needs to be concluded."